The present invention relates to an apparatus for treating a liquid with ion exchange resins, more particularly to a home water softener apparatus equipped with a mechanism that controls automatically a regeneration cycle of the ion exchange resins.
The present invention more particularly is directed to a home water softener of the type including a treatment tank or container that includes a bed of ion exchange resins. After a certain treatment time during which the resins seize unwanted ions in the water to be treated and replace them with more desirable ions, the resins become exhausted or depleted. Once the resin bed is exhausted, treatment no longer is efficient. However, the exhausted resin bed can be regenerated by the introduction into the resin bed of a brine solution to reverse the ion exchange process. Thus, the resin bed regains its original exchanging capacity.
Devices are known to start automatically the cycle of regeneration by closely monitoring when regeneration is needed and by being programmed to start regeneration at certain intervals. One known device employs a "volume" type of regeneration which is programmed to initiate regeneration every time a selected volume, for example three cubic meters, of liquid has been treated by the water softener apparatus. Regeneration then is activated by a volume control unit and starts at the precise moment of anticipated exhaustion of the resins after a certain volume of water has flowed therethrough. However, since regeneration takes place in the treatment tank itself, the user of the water softener is without treated water during the regeneration cycle.
Other known devices remedy more or less satisfactorily this major drawback by activating the regeneration cycle during periods of anticipated non-use, for example during the night. Thus, some such devices employ so-called "time" regeneration which is activated every given number of days and at a particular time of the day, for example by simple timers, for instance every third day at 2:00 a.m. Other such known devices employ "volume with a time adjustment" regeneration that starts after treatment of a given volume of liquid, but always at an anticipated period of non-use, for instance after a treatment of three cubic meters of liquid but at 3:00 a.m.
A disadvantage of these systems is that they cannot take into account variations in water consumption. Such devices therefore must be set for a maximum use. This however causes a 20 to 30% efficiency loss due to waste of salt and energy.
To avoid both a drop in efficiency and the loss of water use during the regeneration cycle, it is known to install two water softeners that operate alternately. This so-called "alternating" regeneration is activated dependent upon the volume of water that passes through each softener. Regeneration starts immediately after exhaustion is reached, and one softener operates while the other is being regenerated until the cycle of the first softener ends. However, this type of system has the drawbacks that it requires a double installation and therefore twice as much floor space and a substantially higher cost, and since the reserved softener can remain inactive for several days, bacteria can develop therein and remain in the treated water.